The traditional lathe is mainly used to test the workpiece by cutting the workpiece, that is, turning the workpiece, finely measuring the size of turning, calculating the difference between the measured value and the target value, according to the size of the difference and the positive and negative feed or retract. For CNC lathes, with the exception of a few equipped with tooling functions, tool setting tools, countersunk blocks, or trial cuts are used. Using a special tool setting tool for external tool setting, although the precision is high, the tool must be aligned with the tool holder. Can be generally relatively heavy knife, disassembly is more laborious. Especially when only replacing the blade, using this method is slower than using a test-cutting knife. With the knife block cutter, due to the influence of various errors, the accuracy of the knife is not high. Therefore, at present, most CNC lathes still use test-cutting workpieces. The first three steps of the procedure are the same as for the lathe's conventional knife, but instead of changing the dial to the tool, use the button to enter the tool compensation value.